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In a retrospective study, adding hyperacute MRI to CT/CTA appeared to be associated with fewer patients receiving acute endovascular stroke therapy compared with CT/CTA alone.

Endovascular stroke therapy in those who received hyperacute MRI was associated with a more favorable outcome and reduced mortality.

When considering patients with acute strokes for endovascular therapy, an MRI might help select those who will be most likely to benefit, a retrospective study suggested.

A protocol that added MRI to the standard CT-based assessment was associated with a lower percentage of patients who underwent endovascular therapy (51.7% versus 96.6%, P<0.05), but a greater percentage who achieved a good clinical outcome at 30 days (23.6% versus 9.1%, P=0.01) compared with a CT-based approach alone, according to M. Shazam Hussain, MD, of the Cleveland Clinic, and colleagues.

Although only a handful of centers around the U.S. are using MRI in this way, "we think that this will probably become a more widely accepted way of selecting patients," Hussain told MedPage Today. "Of course, this is preliminary data. We do need more data along these lines to really prove that this is an effective way to select patients, but it certainly enters us into the discussion on this topic."

Intravenous thrombolytic therapy has been shown to improve outcomes when administered shortly after the onset of an acute stroke, but few patients receive the treatment. Another option is endovascular therapy, which includes mechanical thrombectomy, angioplasty or stenting, and intra-arterial thrombolytics.

Hussein said clinical experience indicates that these alternate treatments work, but recent trials -- including the IMS III and the SYNTHESIS Expansion trials presented last year at the International Stroke Conference -- have not shown a significant benefit. He said the trial failures could be a reflection of suboptimal patient selection.

After looking at their own data, Hussain and his colleagues determined that CT probably wasn't giving them all of the information they needed to select patients for endovascular stroke therapy. They implemented a protocol that added MRI, which provided more information about the size of the infarct and the amount of salvageable brain tissue.

The current analysis included 88 adult patients with large vessel occlusions considered for endovascular stroke therapy before MRI was added to the standard CT-based protocol and 179 considered after the protocol change. In both time periods, the endovascular team was activated as soon as CT angiography showed a large occlusion.

Although there were no differences in stroke severity between the two time periods, the percentage of patients who received IV thrombolytics was numerically -- although not significantly -- lower in the pre-MRI period (36.4% versus 46.6%, P=0.12).

After MRI was added to the protocol, the number of patients who actually received endovascular therapy dropped, but the percentage of patients who had a good clinical outcome -- defined by a modified Rankin Scale score of 2 or lower -- increased and the percentage who died decreased. Outcomes were better among the patients overall and among those who received endovascular treatment.

The findings held up in a multivariate analysis; at 30 days, endovascular therapy performed after MRI was added to the protocol was still associated with an increased likelihood of a good clinical outcome (OR 3.4, 95% CI 1.1-10.6) and reduced mortality (OR 0.16, 95% CI 0.06-0.37).

Countering concerns that adding MRI could delay treatment, the average time from stroke onset to the first run of endovascular therapy was no different before than after MRI was added to the protocol (407 versus 390 minutes, P=0.81).

The authors acknowledged that their analysis was limited by the retrospective, single-center design and by the inability to account for factors that might have changed over time and influenced the results.

Hussain noted that another concern with adding MRI is cost and said that he and his colleagues are currently looking at whether their approach is cost-effective.

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